Reed telephone receiving



Oct. 30, 1923.

- G. w. PICKARD REED TELEPHONE RECEIVING Filed Nov. 19. 1920 Patented Oct. 30, 1923.

UNITED STATES PATENT OFFICE.

GREENLEAF WHITTIER PICKARD, OE NEWTON CENTER, MASSACHUSETTS, ASSIGNOE TO WIRELESS SPECIALTY APPARATUS COMPANY, OF BOSTON, MASSACHUSETTS, A

CORPORATION OF NEW YORK.

REED TELEPHONE RECEIVING.

Application filed November 19, 1920. Serial No. 425,058.

PIOKARD, a citizen of the United States of- America, and a resident of Newton Center,

'State of Massachusetts, have invented certain new and useful Improvements in Reed Telephone Receiving, the principles of which are set forth in the following s ecification and accompanying drawings, w ich disclose the form of the invention which I now consider to be the best of the various forms in which the principles of the invention may be embodied.

This invention relates to electromagnetic reed telephone receiving for use in either radio or wire communication of either telephonic or telegraphic intelligence, and especially in the telephonic reception of telegraphic communication involving currents of definite audio frequency supplied to the telephone receiver.

One of the principal objects of the invention is to secure maximum practicable resonance to input currents of definite audio frequency, and also to provide a construction which is simple and inexpensive to construct, of a rugged character in service, and very sensitive to feeble electrical impulses.

Another important object is to provide a construction whereby the mechanical tune of the reed telephone can be altered at the will of the user.

The invention consists of the various novel features hereof and their co-operative organization including the magnetic system, the vibratory reed, the sound-producing diaphragm and the coupling member between them, all as disclosed and described herein.

The drawin is a perspective view of a modified embodiment of magnet system and reed providin a variability of the mechanical tune of t e reed by the user or operator.

The ordinary electromagnetic or Bell type of telephonic receiver does .not employ me;

ciating with the magnetic circuit an element having such a shape as a diaphragm in such wise as to secure maximum effect of the input current on the diaphragm. Also the magnetic circuit being adapted to-the arrangement of the diaphragm of that type of receiver has not been itself of the-most etlicient form. In the production of my receiver, I have devised initially a very efficient magnetic circuit and then, in order to most effectively use the same, have resorted to'the principle of the reed telephone and have devised a coupling member for the purpose of mosteffectively controlling the transmission of the energy of the input current, acting upon my eflicient magnetic circuit, from the'reed to a sound-producing diaphragm arranged in. another plane generally more or less parallel'to the plane of the magnet system, close to the position of the ope-rators ear and coupled to the reed. The principle of the reed telephone has been applied to selective work but not in nearly as eflicient form as herein, either in respect of the magnet system or of the practical emloyment of mechanical resonance. In my invention, the relation of the diaphragm system to the reed is such as to enable the reed and diaphragm to vibrate efliciently in resonance with the frequency of the input current without blurring of successive sounds produced by the diaphragm.

The above-described magnetic organization, in co-operation with the tuning of the reed and a s ecial coordination of diaphra m and reed to e described, is especially useful in radio telegraphy (as to the very important feature of selectivity) in either of two radio systems in general use as follows.

The first is the spark s stem where the frequency is used of the or er of a thousand sparks per second (audio frequency) as employed with so-called impact or quenched spark transmitters, and where there is set' 1100, the reed will be tuned to 1000. y

The second system is that of undamped or ,that is, if the frequency ranges from 900 to 1o, 11 Fig will be continuous wave transmission by various ipes of transmitters wherein at the receiver t e so-called beat system is used (at audio frequency) or other means of converting the continuous wave Signal current into an audio frequenc signal current (such as the rotary tone con enser of the patent of Proctor, No. 1,211,963 of January -9, 1917), in any of which systems the resultant input current in the circuit of the tele hone receiver (coils 2) is pure iy sinusoidal and its frequency is under the control of the operator. Said magnetic organization is especially useful for suchpurposes when it is permitted to take the fullest practicable advantage of receiver resonance by means-of the construction, hereinafter described, of

the diaphragm s stem, consisting of the sound-producing iaphragm 3 and the means 17 for coupling it with tuned reed 14.

It is of the utmost importance in receiving continuous wave signals in radio to utilize mechanical resonance in the telephone to the greatest degree consistent with the prevention at blurring of signal sounds. This importance is due to the large and rapidly-increasing number of continuous wave transmitters, many of which have approximately the same radio frequency. In this situation,

the result (in the lack of a suitable telephone receiver heretofore) has been in the teleghone such multiplicity of signal sounds of ifierent pitches as to confuse the operator, thisnotwithstanding his em loyment .of the best radio tuning means an of his selectionat will of an optimum note for the signal desired to be observed. I have found that without the invention hereof, when a tuned reed receiver is constructed so as to take full advanta e of resonance, the signal sounds fiurred, and that when a tuned need receiver is constructed so that the si alsounds are not blurred, the utilization of resonance will not be involved'to' an extent sufiicient to exclude undesired signals. The receiver of the invention hereof is one-in which the signal sounds are not blurred and also where resonance is taken advantage of to the greatest practicable extent consistent easy reception with non-blurring, whereby exclude all unis secured with the ability to desired signals.

In cases where a feebly-damped mechanical receiving system is em loyed (therebv using resonance to the ful est extent), not only is an appreciable fraction of a second required for the building-up of the amplitu e of mechanical vibration of such system to its maximum value, but an equal time is required for the dying-away of such vibrations after the cessation of the input signal current. Such unrestrainedprolongation of signal sound interferes with telegraphic-signaling because it tends to obliterate the interval between successive groups of vibra tions of the mechanical system which con stitute the signals. In other words, the sounds representing the telegraphic dots and dashes Wlll run together or be blurred, in manner as if the si naling were attempted on a harpstring. IE on. the other hand, the mechanical system is highly damped, it will .lack the advantages of the cumulative effect of resonance and the accompanying advantage of selectivity" (i. e.,'the power to exclude foreign signals of different frequency by means of mechanical resonance), so that the resulting signal note will be weak although clearcut and not blurred.

One of the objects hereof is to provide such construction of the diaphragm system,

as to either the diaphragm or its coupling with the reed, or both, as to take fullest possible advantage of resonance Without producing blurring, in order to prevent the proxluction of signal notes in a telephone from undesired s1 nals having a radio frequency (much'greater than the reed) to effect such purpose; The location of the diaphragm also is nearer to the ositionuofthe operators car than it would e practicable. to locate the reed itself. But even with'the eflicient magnetic system above described, the ciliciency of (ooperation of a'reed tuned to the input current and a diaphra coupled to the reed is greatly increased w en the abovestated object of using resonance to the greatest possible extent without blurring is accomplished; that is, of course, in case of adaptation to use with signals] having definite frequency of input current. I

In the drawing is shown a form of the invention particularly adapted to damp wave transmission, but also of very great utility in continuous wave reception. Y

In the drawing is shown a form of reed 0r vibratorymember 14 fixed at both its ends as by screws at F, F to the ends or spaced parts of a U-shaped member M of magnetic material, slightly resilient, which forms part of the circuit of the polarizing ma' ct which includes also the part 11, and t e reed 14 and also the laminated short and nearlyclosed electromagnet core 4. Magnet 11; is.

magnetically associated with core 4 at 12 t and with member M at 13. The input circuit is to be wound on core 4.

In the drawing the portion 15 of maximum 7 amplitude of vibration of reedl lies in gap 8 between ends 6 and 7 of core Diaphragm 1 3 and the entire system may be mounted or supported in any desired way, and the diaphragm and reed are coupled in accord with the, intermediacy of coupling described fully below. Coupling 17 in this case may comprise two members as shown, connected to the reed symmetrically on opposite sides of core 4 at such points on the reed as determined to produce the results of this invention and joined together at point 19 to a common member connected to a central point on diaphragm 3. Coupling 17 may include resilient portion 17 (in dotted lines in any case where the desired interme iacy of coupling is not obtained alone by points of connection to the reed intermediate the portion 15 of maximum amplitude of vibration and its fixed ends F.

In the drawing, screw -W is threaded at H to engage in adjacent leg member M and has its other end abutting against the side of the opposite leg of M, so that the user may adjust the tension and hence the tune of reed- 14 mounted on M by forcingithe legs more or less apart. .The thread at is preferably fine in order to permit fine adjustments 0 tuning. This form is especiall adapted to use in receiving spark or dampe wave transmission wherein the audio frequency at the receiving station is .fixed by the transmitting apparatus and not adjusted by the operator as in continuous wave transmission. Thus the operator in this case tunes the reed to the fixed audio frequency instead (as in continuous wave transmission) of adjusting the audio frequency at the receiver to a fixed tune of the reed.

a to such a beat rate or audio frequency produced by the desired signal as will be as distinct from the beat rate or audio frequenc produced by an interfering'signal as is possible by selection, as, for example, of heat note alone; thereupon the operator can tune the reed to that beat note of the desired signal, with the result of either preventing the reed from responding at all to the rate of the interfering signal or at least reducing the interfering response to such extent as to insure easy reading of the desired signal, no

matter how great the intensity of the interfering signal as it reaches the receiving method involved in the operation of the form of the drawing. In a receiver which is very efficiently and sensitively organized electromagnetically, there is provided a construction which permits the utmost practicable utilization of the principle of mechanical resonance by virtue of the tuning of the reed to the audio frequency of the input current, and such resonance is permitted to be employed without resulting in blurring of the signal-sounds by virture of the design of the diaphragm system including diaphragm and coupling co-operatively with the reed as a part of the magnet system, with the result of producing a signal sound which in time duration corresponds with the time duration of the signal input current which itself corresponds with the transmitted signal, thereby preventing the running together or blurring of signal sounds without damping the f reed to such an extent as to materially reduce the advantage of resonance, all where by foreign or undesired signal sounds may be excluded. l

By intermediate coupling or damping referred to above is meant such damping that, on the one hand, the reed and diaphragm are not allowed to vibrate in response to an input signal over a period of time covering the interval between the given signal and the next succeeding signal, and, on the other hand, the reed and diaphragm are permitted I to vibrate a sufficient lengthof time in response to a given input signal to take the fullest practicable advantage of the cumula tive effect of resonance with the accompanying advantage of selectivity.

It is to be understood that the invention is not limited to the embodiments and features specifically shown and described herein, but that such embodiments and features are subject to changes and modificationswithout any departure from the spirit of the invention.

I claim 1. In a telephone receiver, an electromagnetic, nearly-closed circuit having a gap, a winding for the input current associated with said electromagnetic circuit, a polarizing magnet magnetically connected to said electromagnetic circuit at one end whereby the portions of the electromagnetic circuit on opposite sides of the gap are of the same polarity, the opposite end of said polarizing magnet terminating in a resilient U-shaped member, a vibratable reed secured at its outer portions to the legs of said U-shaped free to vibrate and located within said gap,

said reed being of the opposite polarity to that of the electromagnetic circuit, an adjustin screw'engaging the legs of said U- shapedimember for varying the amount of separation thereof to tension said reed for tuning, and a diaphragm connected to said ree 2. In a telephone receiver, a nearly-closed electromagnetic core, a windingfdir, the input current associated'with said core, a polarizing magnet magnetically connected to said core at oneend, the other end of said polarizing magnet terminating in -a U- shaped member having its legs adjacent the gap between the ends of the nearly-closed electromagnet core and on opposite sides of said gap;-avibratable reed outer portions 'to the legs of said U-shaped member and having an intermediateportion free to'vibrate and located within said gap; an adjusting screw engaging the legs of said U-shaped member for varying the amount of separation thereof to tension said reed for tuning, and a diaphragm connected to said reed.

' 3. In a telephone receiver, a magnetic circuit constructed with a gap in one end and havin the other end terminating in a U shaped member having its legs adjacent said gap and on opposite sides thereof; a vibratable reed having its outer portions secured to the legs of said .U-shaped member and having an intermediate portion located in said gap and free to vibrate therein; and an adjusting screw engaging the legs of the U- shaped member. .7

secured at its 4. In a telephone receiver, an electroma net core having a gap in one end, a magnetic U-shaped member magnetically linkediwjth said core and having its legs located adjacent said gap and on opposite sides thereof; a

winding on said core; a vibratable reed having its outer ortions secured to the legs of said U-shape member and having an intermediate portion located in said gap and free to vibrate therein; and an adjusting screw engaging the legs of the U-shaped member.

5; n a telephone re'ceiver,-an .open magnetic circuit one end of which comprisesa nearly-closed laminated electromagnet core and the other 'end of which comprises a vibratable reed extending through the gap between the endsof the nearly-closed electromagnet core; an intermediate portion of the magnetic circuit comprising a U-shaped part having its legs located alongside said coregap and having said reed secured to its legs; 7

and an adjusting screw engaging the legs of the U-shaped member.

6. In a telephone receiver, the combination with a magnet system and a vibratable reed,

of a diaphragm and means for coupling thediaphragm and reed; of means for adjustin the reed which comprises a U-shaped end 0 the magnetic circuit of the magnet system on Y the legs of which the reed is secured; and an adjusting screw engaging said CREENLEAF WHITTIER PICKA'RD. Witnessesz.

Bow. 0. Peanut,

WILLIAM-H. Pnmss. 

